A variety of powered mechanisms have been engineered to raise and lower garage doors, but most contemporary residential garage door openers use a chain-driven system. This particular design uses a chain-on-sprocket to move the door into its positions; it is a time-tested, reliable, and low-cost mechanism. However, even the best mechanical systems can malfunction from time-to-time, and your chain-driven garage door is no exception. Below is more information on this system and how you can troubleshoot it to see if it will need servicing:

Understanding your chain-driven garage door opener

The chain-driven system used with garage door openers is similar to that found on a bicycle. A long chain is looped around a sprocket extending from the opener case; the other end of the chain is looped around a free-wheeling sprocket located near the wall above the doorway. The door trolley, which "rides" abreast the central rail that also serves as structural support, is attached to middle of the chain. In turn, the trolley is attached to the garage door itself via a locking mechanism and lever.

When the door opener is activated, it rotates the powered sprocket which moves the chain one direction or the other. The attached trolley moves up and down the rail, pushing and pulling the garage door as it goes.

Problems caused by a slack chain

In most chain-driven garage door openers, the chain should hang above the central rail between one-fourth and one-half of an inch at its lowest point. If the chain hangs lower than that, problems can occur. Here are some issues that you might experience with a slack chain:

Excess sprocket wear – a slack chain is subject to slipping, and when it does, it rubs against the sprocket teeth and can wear them down over time. This, in turn, makes slipping worse and the chain will continue to grow more slack.

Chain wear and breakage – a slack chain will rub against the rail, and this can cause a chain to prematurely wear. Slipping chains are also more likely to break due to the strains placed upon them by the sprocket teeth rubbing against them.

Chain dislocation – if the chain becomes too slack, it can fall off the sprocket entirely. A falling chain can cause serious damage should it strike your car, including cracking windshields or denting body panels, and it could also injure someone if they are underneath at the time.

Excessive noise – a slack chain will create noisier operation as the chain slips and buffets, and the door will shudder, as well.

Problems caused by a tight chain

An overly-tight chain can also create problems for the smooth operation of your garage door. Below are some of the issues caused by chains that are too-tight:

Bearing failures – one of the most expensive problems caused by a chain that is too tight is motor bearing failure. A tight chain will put continual horizontal pressure on the sprocket shaft, which in turn pulls against the motor and its bearings. This pressure wears out the bearings and internal components, and the expensive result may be an unexpected purchase of a new motor or opener.

Chain wear and breakage – just as a slack chain can cause undue wear-and-tear, a too-tight chain will also break down much faster. The stress of being pulled too tightly can fatigue the metal links, and the chain will also rub too closely against the sprocket teeth.

Excessive noise – an overly-tight chain will also generate a lot of noise as it grinds, rubs and pulls against the metal components in your system. It can cause the door to bind, as well, which may affect your wheel tracks.

What to do if your chain is improperly tightened

If you believe your garage door opener chain isn't properly tightened based on the amount of distance it hangs down above the rail, or you are experiencing any of these problems, then you need to learn more here or contact a garage door professional for help. Adjusting the chain is a fast repair for garage door installers and repairers, and it can save you a lot of money by avoiding expensive damages caused to your opener, door or even your vehicles.

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About Me

Hello, my name is Bonny Cooke. Welcome. I am here to talk to you about large equipment and tools used in the construction field. When a construction company began erecting a huge apartment building next door to my dwelling, I was given a crash course on heavy equipment and tools. I instantly fell in love with the way the machinery effortlessly completed each task to move the project forward. On this site, I hope to explore the various functions of each type of equipment and tools used on construction sites. Please feel free to come by on a routine basis to learn all you can about this subject.